Summary: Free-volume kinetic models of granular matter
Mauro Sellitto
Laboratoire de Physique de l'E´cole Normale Supe´rieure de Lyon, 46 Alle´e d'Italie, 69007 Lyon, France
Jeferson J. Arenzon
Instituto de Fi´sica, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, 91501-970 Porto Alegre,
Rio Grande do Sul, Brazil
Received 6 April 2000
We show that the main dynamical features of granular media can be understood by means of simple models
of fragile-glass-forming liquid Kob and Andersen, Phys. Rev. E 48, 4364 1993 provided that gravity alone
is taken into account. In such lattice-gas models of cohesionless and frictionless particles, the compaction and
segregation phenomena appear as purely nonequilibrium effects unrelated to the Boltzmann-Gibbs measure,
which in this case is trivial. They provide a natural framework in which slow relaxation phenomena in granular
and glassy systems can be explained in terms of a common microscopic mechanism given by a free-volume
kinetic constraint.
PACS number s : 05.70.Ln, 61.43.Gt, 64.70.Pf
Vibrated powders are one of the most interesting ex-
amples of nonequilibrium systems where excluded-volume
interactions are known to play a crucial role. Based on the
free-volume notion, the analogy with glassy dynamics and
its limit was recognized early 1 . Indeed, the static and